Why everyone prefers ZX279125 chipset ONU?? What all things you need to check before you buy a ONU?

Ordinary ZTE ONU'S	ZTE ONU
Modules were refurbished Old chipset will not filter the illegal dhcp and pppoe server from onu GE Low quality materials Used Network Issues increases	New model will filter the illegal DHCP and PPPOE server from onu GE New Chipset support rouge ONU checking SDRAM is inside the chipset ( helped to provide industry standard performance )

What all things you need to check before you buy a ONU? Lets compare ordinary ZTE ONU annd ZTE ONU